Random Wire Antenna with Ground Radial System (inverted “L”)

Over the last two weeks I have been putting together a ground counterpoise system to go along with my random length antenna (see original post).

I started with a basic radial plate (DX Engineering) and purchased a kit that included 500ft of wire and various hardware for 20 radials.

To get started…I decided to build myself a quick spreadsheet to determine the lengths of radials I wanted, per band, and to determine if I had enough wire to finish the job. This is what I ended up with:

Excel File

With a little bit of planning, I determined that I could get my longest radials nearly 180° from each other off my radial plate if I ran one radial to the back corner and took the other radial down the side of my house. Furthermore, I believed that I could achieve the most vertical height out of my antenna if I placed my radial plate directly near the base of the tree (nearest to my shack). My basic design is as following (not all details about antenna and radials are shown):

HouseOverview

Building the radials went rather quickly using the fancy wire strippers I also ordered from DX Engineering. I made the mistake of thinking this would take me the longest amount of time…cause once I got outside…it took me forever to get the lines laid out and then bolted/staked into place. I started with the longest wires first then worked my way “up the bands” to the shortest wires trying to get them more evenly distributed around fences, trees, decks, garden, and the trampoline. It was at this point that my wife began wonder if I was building a set of electrified “trip wires” to take out my kids and pets :).

My radial plate looks like this (see below). Pay attention to the wire strain relief and camping stakes (used to hold the base plate in place…four aluminum on the sides, and one orange in the center).

Acworth-Kennesaw-20140308-00133Acworth-Kennesaw-20140308-00132

NOW TO WORK ON THE RANDOM LENGTH WIRE ANTENNA

With 75ft of wire left on the spool, after building the radials, I had the perfect length for 8 bands length I was shooting for (see purple in diagram).

Shooting lines through the first tree was the most challenging part because I had a certain path I wanted the wire to exit at the top of the tree (where the wire goes from vertical to horizontal towards the neighbor tree). I must have made 20 shoots with the slingshot to make it. It actually took two precise shots…one for the rope to pull up the isolator used to make the turn from vertical to horizontal (this one was easy) and one to make the path for the wire antenna (this is the one that took multiple tries).

To illustrate the path…starting from the at the far end of the random wire I attached isolator and connected it via rope to a heavy duty bungee cord.
EndAntenna

I then routed it to a plastic clothesline pulley I found at Home Depot.
pulley

Here is the last turn (not illustrated good here but you get the idea).
Antenna Vertical

Lastly…I placed coax seal around the connection point (using electrical tape first, then coax seal, then more electrical tape…it looks ugly because I had issues going underneath…it wasn’t neat…but will get the job done.
Acworth-Kennesaw-20140308-00139

HOW DOES IT WORK?

Here is plot showing the full range from 0 to 54Mhz. You will notice a number of dips in the SWR (this scale only goes up to 6) in the plot (yellow areas approx. the amatuer radio band plans). In some cases this is good…in others…not so good.
Full Range

80M was a surprise:
80M

12M, 17M, and 30M did not look to bad either:
12M

17M

30M

However, when I took a closer look at 20M and 40M I noticed that they were not doing well (my areas of improvement):
multibandswr

Thankfully the tuner on my KXPA100 (the KX3 AMP) tunes them to down around 1.2 or so so I should be able to work with those bands until I can figure out some changes to experiment with.

All in all…I am happy so far with the antenna progress. Now to see if works better than the attic dipole that I have.

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4 thoughts on “Random Wire Antenna with Ground Radial System (inverted “L”)

  1. I would be interested to hear you thoughts now that you have been on the air with this antenna for a few months. I am thinking of doing something similar at my HOA controlled QTH. Right now I have a 66′ dipole fed with ladder line in the attic. Noise level of S5 most of the time, and it also seems to have a bit of a time hearing weaker stations.

    My thought is getting wire outside will have to help – but how does the noise compare on your long wire vs the attic dipole?

    Also are your isolators pulled over large branches or just kindof over some smaller branches? It looks like the just kindof lay over some smaller branches.

    Also do you have a balun somewhere in the mix?

    Sorry for all the questions – you are the one guy that has done something similar to what I am looking to do!

    • Hi Burke,

      I have been doing well with my attic fan dipole…but have found two major sources of noise (old TV and washing machine)…which both can be controlled. I wonder if the source of your S5 noise is in your house. May be worth exploring.

      Outside antenna is noticeably more quiet based on what I noticed first with the new antenna. Unfortunately it came down a few weeks ago before I really had a chance to use it and before I could do a more in depth comparison. Unfortunately I did not do a good job on the far end ensuring that it would stay connected. I think it just got loose (or kids pulled it down).

      Since my trees are fairly small…I really don’t have much choice but to go over small limbs to get the height I desire.

      When the leaves fall again I will put the antenna back up (and bury a few radials that remain uncovered by grass).

      Monty

  2. any updates? planning to do something simlar using a Icom AH-4 tuner – in a HOA restrcited area – thanks Mark KI4AOX

    • Hi Mark, unfortunately no. Antenna came down in storm shortly after I put it up. Have your not had a chance to put it back up. I think a radial setup with the AH-4 tuner is a great idea.

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